# Given a column title as appear in an Excel sheet, return its corresponding column number.
#
# For example:
#
#     A -> 1
#     B -> 2
#     C -> 3
#     ...
#     Z -> 26
#     AA -> 27
#     AB -> 28
#     ...
# Example 1:
#
# Input: "A"
# Output: 1
# Example 2:
#
# Input: "AB"
# Output: 28
# Example 3:
#
# Input: "ZY"
# Output: 701


class Solution:
    def titleToNumber(self, s):
        Sum = 0
        for exp, char in enumerate(s[::-1]):
            Sum += (ord(char) - 65 + 1) * 26 ** exp

        return Sum
